In the Cage
Omega Haru, brought up in a trash family made to feel like trash until he meets sibling brothers who fall for him at a ball. Unfortunately, Eiji feels threatened by his older brother's presence and by Haru's reaction to Renji so does douchebag things to make it seem like Renji has no feelings for Haru. However, Renji separated from Haru to get away from his toxic family and make a name for himself to claim Haru whom he recognized as his fated pair. He left him a letter which Eiji discovered and hide from him. For a while, when Renji was abroad, Eiji and Haru have a relationship but he was always the side dish since Eiji had a fiancee. When Renji returns things gets cleared up, feelings mature and intensify and although Eiji comes clean about his actions, there's no room for him anymore. Renji ultimately becomes mates with Haru. Happy ending! (Except for the attempted rape on Haru by some rando alphas perpetrated by Eiji's fiancee out of jealousy) meh
Sayonara, Itoshi No My Friend